When any sign of longships is spotted, elders in watchtowers light beacon fires, which in turn cause other watchtowers to light their own beacons and spread the warning to settlements further inland so they will not be caught unaware.[2]

The Misty Islands were renamed the Shield Islands once Garth VII Gardener drove out the ironmen and fortified them with men from the Reach.[6] The Gardener kings armed the fisher folk of the Shield Islands to protect not only themselves, but also the river, thus giving the islands their name.[2]

A Dance with Dragons

Quotes

In ancient days, the ironborn had boldly sailed the river road and plundered all along the Mander and its vassal streams ... until the kings of the green hand had armed the fisherfolk on the four small islands off the Mander's mouth and named them his shields.[2]